Toxic emissions from mobile sources: a total fuel-cycle analysis for conventional and alternative fuel vehicles

Mobile sources are among the largest contributors of four hazardous air pollutants--benzene, 1,3-butadiene, acetaldehyde, and formaldehyde--in urban areas. At the same time, federal and state governments are promoting the use of alternative fuel vehicles as a means to curb local air pollution. As yet, the impact of this movement toward alternative fuels with respect to toxic emissions has not been well studied. The purpose of this paper is to compare toxic emissions from vehicles operating on a variety of fuels, including reformulated gasoline (RFG), natural gas, ethanol, methanol, liquid petroleum gas (LPG), and electricity. This study uses a version of Argonne National Laboratory's Greenhouse Gas, Regulated Emissions, and Energy Use in Transportation (GREET) model, appropriately modified to estimate toxic emissions. The GREET model conducts a total fuel-cycle analysis that calculates emissions from both downstream (e.g., operation of the vehicle) and upstream (e.g., fuel production and distribution) stages of the fuel cycle. We find that almost all of the fuels studied reduce 1,3-butadiene emissions compared with conventional gasoline (CG). However, the use of ethanol in E85 (fuel made with 85% ethanol) or RFG leads to increased acetaldehyde emissions, and the use of methanol, ethanol, and compressed natural gas (CNG) may result in increased formaldehyde emissions. When the modeling results for the four air toxics are considered together with their cancer risk factors, all the fuels and vehicle technologies show air toxic emission reduction benefits.     

Toxic Emissions from Mobile Sources: A Total Fuel-Cycle Analysis for Conventional and Alternative Fuel Vehicles

ABSTRACT

Mobile sources are among the largest contributors of four hazardous air pollutants—benzene, 1,3-butadiene, acetal-dehyde, and formaldehyde—in urban areas. At the same time, federal and state governments are promoting the use of alternative fuel vehicles as a means to curb local air pollution. As yet, the impact of this movement toward alternative fuels with respect to toxic emissions has not been well studied. The purpose of this paper is to compare toxic emissions from vehicles operating on a variety of fuels, including reformulated gasoline (RFG), natural gas, ethanol, methanol, liquid petroleum gas (LPG), and electricity. This study uses a version of Argonne National Laboratory's Greenhouse Gas, Regulated Emissions, and Energy Use in Transportation (GREET) model, appropriately modified to estimate toxic emissions. The GREET model conducts a total fuel-cycle analysis that calculates emissions from both downstream (e.g., operation of the vehicle) and upstream (e.g., fuel production and distribution) stages of the fuel cycle. We find that almost all of the fuels studied reduce 1,3-buta-diene emissions compared with conventional gasoline (CG). However, the use of ethanol in E85 (fuel made with 85% ethanol) or RFG leads to increased acetaldehyde emissions, and the use of methanol, ethanol, and compressed natural gas (CNG) may result in increased formaldehyde emissions. When the modeling results for the four air toxics are considered together with their cancer risk factors, all the fuels and vehicle technologies show air toxic emission reduction benefits.     

Comparing lifetime emissions of natural gas and conventional fuel vehicles: an application of the generalized ANCOVA model

New regulations and incentives are encouraging the use of clean, alternative fuel vehicles (AFVs) in urban areas. These vehicles are seen as one option for reducing air pollution from mobile sources. However, because of the limited number of AFVs on the road, little is known about actual lifetime emissions characteristics of in-use AFVs. This study describes the use of a generalized analysis of covariance model to evaluate and compare the emissions from natural gas vehicles with emissions from reformulated gasoline vehicles. The model describes fleet-wide emissions deterioration, while also accounting for individual vehicle variability within the fleet. This ability to measure individual vehicle variability can then be used to provide realistic bounds for the emissions deterioration in individual vehicles and the fleet as a whole. In order to illustrate the use of the model, the carbon monoxide, oxides of nitrogen (NOx), non-methane hydrocarbon (NMHC), and carbon dioxide emissions characteristics of a fleet of dedicated natural gas Dodge Ram vans and a fleet of dedicated reformulated gasoline Dodge Ram vans operating in the U.S. government fleet are explored. The analysis demonstrates the utility of the statistical method and suggests a potential for natural gas Dodge Ram vans to be generally cleaner than their conventional fuel counterparts. However, in the case of NOx and NHMCs, the analysis also suggests that these emissions benefits might be reduced over the vehicle lifetime due to higher emissions deterioration rates for natural gas vehicles. As this paper is aimed at illustrating the analysis of the covariance model, the results reported herein should be considered within the context of a more comprehensive study of these data before general conclusions are possible. Generalization of these findings to other vehicle models and alternative fuel technologies is not justified without further study.     

Diesel engines: environmental impact and control.

The diesel engine is the most efficient prime mover commonly available today. Diesel engines move a large portion of the world's goods, power much of the world's equipment, and generate electricity more economically than any other device in their size range. But the diesel is one of the largest contributors to environmental pollution problems worldwide, and will remain so, with large increases expected in vehicle population and vehicle miles traveled (VMT) causing ever-increasing global emissions. Diesel emissions contribute to the development of cancer; cardiovascular and respiratory health effects; pollution of air, water, and soil; soiling; reductions in visibility; and global climate change. Where instituted, control programs have been effective in reducing diesel fleet emissions. Fuel changes, such as reduced sulfur and aromatics content, have resulted in immediate improvements across the entire diesel on- and off-road fleet, and promise more improvements with future control. In the United States, for example, 49-state (non-California) off-road diesel fuel sulfur content is 10 times higher than that of national on-road diesel fuel. Significantly reducing this sulfur content would reduce secondary particulate matter (PM) formation and allow the use of control technologies that have proven effective in the on-road arena. The use of essentially zero-sulfur fuels, such as natural gas, in heavy-duty applications is also expected to continue. Technology changes, such as engine modifications, exhaust gas recirculation, and catalytic aftertreatment, take longer to fully implement, due to slow fleet turnover. However, they eventually result in significant emission reductions and will be continued on an ever-widening basis in the United States and worldwide. New technologies, such as hybrids and fuel cells, show significant promise in reducing emissions from sources currently dominated by diesel use. Lastly, the turnover of trucks and especially off-road equipment is slow; pollution control agencies need to address existing emissions with in-use programs, such as exhaust trap retrofits and smoke inspections. Such a program is underway in California. These and other steps that can be continued and improved will allow the use of the diesel engine, with its superior fuel consumption, to continue to benefit society while greatly reducing its negative environmental and health impacts. The next ten years can and must become the "Decade of Clean Diesel."     

Source apportionment of ambient non-methane hydrocarbons in Hong Kong: application of a principal component analysis/absolute principal component scores (PCA/APCS) receptor model

Receptor-oriented source apportionment models are often used to identify sources of ambient air pollutants and to estimate source contributions to air pollutant concentrations. In this study, a PCA/APCS model was applied to the data on non-methane hydrocarbons (NMHCs) measured from January to December 2001 at two sampling sites: Tsuen Wan (TW) and Central & Western (CW) Toxic Air Pollutants Monitoring Stations in Hong Kong. This multivariate method enables the identification of major air pollution sources along with the quantitative apportionment of each source to pollutant species. The PCA analysis identified four major pollution sources at TW site and five major sources at CW site. The extracted pollution sources included vehicular internal engine combustion with unburned fuel emissions, use of solvent particularly paints, liquefied petroleum gas (LPG) or natural gas leakage, and industrial, commercial and domestic sources such as solvents, decoration, fuel combustion, chemical factories and power plants. The results of APCS receptor model indicated that 39% and 48% of the total NMHCs mass concentrations measured at CW and TW were originated from vehicle emissions, respectively. 32% and 36.4% of the total NMHCs were emitted from the use of solvent and 11% and 19.4% were apportioned to the LPG or natural gas leakage, respectively. 5.2% and 9% of the total NMHCs mass concentrations were attributed to other industrial, commercial and domestic sources, respectively. It was also found that vehicle emissions and LPG or natural gas leakage were the main sources of C(3)-C(5) alkanes and C(3)-C(5) alkenes while aromatics were predominantly released from paints. Comparison of source contributions to ambient NMHCs at the two sites indicated that the contribution of LPG or natural gas at CW site was almost twice that at TW site. High correlation coefficients (R(2) > 0.8) between the measured and predicted values suggested that the PCA/APCS model was applicable for estimation of sources of NMHCs in ambient air.     

Microscale air quality impacts of distributed power generation facilities

The electric system is experiencing rapid growth in the adoption of a mix of distributed renewable and fossil fuel sources, along with increasing amounts of off-grid generation. New operational regimes may have unforeseen consequences for air quality. A three-dimensional microscale chemical transport model (CTM) driven by an urban wind model was used to assess gaseous air pollutant and particulate matter (PM) impacts within ~10 km of fossil-fueled distributed power generation (DG) facilities during the early afternoon of a typical summer day in Houston, TX. Three types of DG scenarios were considered in the presence of motor vehicle emissions and a realistic urban canopy: (1) a 25-MW natural gas turbine operating at steady state in either simple cycle or combined heating and power (CHP) mode; (2) a 25-MW simple cycle gas turbine undergoing a cold startup with either moderate or enhanced formaldehyde emissions; and (3) a data center generating 10 MW of emergency power with either diesel or natural gas-fired backup generators (BUGs) without pollution controls. Simulations of criteria pollutants (NO₂, CO, O₃, PM) and the toxic pollutant, formaldehyde (HCHO), were conducted assuming a 2-hr operational time period. In all cases, NO_x titration dominated ozone production near the source. The turbine scenarios did not result in ambient concentration enhancements significantly exceeding 1 ppbv for gaseous pollutants or over 1 µg/m³ for PM after 2 hr of emission, assuming realistic plume rise. In the case of the datacenter with diesel BUGs, ambient NO₂ concentrations were enhanced by 10–50 ppbv within 2 km downwind of the source, while maximum PM impacts in the immediate vicinity of the datacenter were less than 5 µg/m³.

Implications: Plausible scenarios of distributed fossil generation consistent with the electricity grid’s transformation to a more flexible and modernized system suggest that a substantial amount of deployment would be required to significantly affect air quality on a localized scale. In particular, natural gas turbines typically used in distributed generation may have minor effects. Large banks of diesel backup generators such as those used by data centers, on the other hand, may require pollution controls or conversion to natural gas-fired reciprocal internal combustion engines to decrease nitrogen dioxide pollution.     

A life-cycle comparison of alternative automobile fuels

We examine the life cycles of gasoline, diesel, compressed natural gas (CNG), and ethanol (C2H5OH)-fueled internal combustion engine (ICE) automobiles. Port and direct injection and spark and compression ignition engines are examined. We investigate diesel fuel from both petroleum and biosources as well as C2H5OH from corn, herbaceous bio-mass, and woody biomass. The baseline vehicle is a gasoline-fueled 1998 Ford Taurus. We optimize the other fuel/powertrain combinations for each specific fuel as a part of making the vehicles comparable to the baseline in terms of range, emissions level, and vehicle lifetime. Life-cycle calculations are done using the economic input-output life-cycle analysis (EIO-LCA) software; fuel cycles and vehicle end-of-life stages are based on published model results. We find that recent advances in gasoline vehicles, the low petroleum price, and the extensive gasoline infrastructure make it difficult for any alternative fuel to become commercially viable. The most attractive alternative fuel is compressed natural gas because it is less expensive than gasoline, has lower regulated pollutant and toxics emissions, produces less greenhouse gas (GHG) emissions, and is available in North America in large quantities. However, the bulk and weight of gas storage cylinders required for the vehicle to attain a range comparable to that of gasoline vehicles necessitates a redesign of the engine and chassis. Additional natural gas transportation and distribution infrastructure is required for large-scale use of natural gas for transportation. Diesel engines are extremely attractive in terms of energy efficiency, but expert judgment is divided on whether these engines will be able to meet strict emissions standards, even with reformulated fuel. The attractiveness of direct injection engines depends on their being able to meet strict emissions standards without losing their greater efficiency. Biofuels offer lower GHG emissions, are sustainable, and reduce the demand for imported fuels. Fuels from food sources, such as biodiesel from soybeans and C2H5OH from corn, can be attractive only if the co-products are in high demand and if the fuel production does not diminish the food supply. C2H5OH from herbaceous or woody biomass could replace the gasoline burned in the light-duty fleet while supplying electricity as a co-product. While it costs more than gasoline, bioethanol would be attractive if the price of gasoline doubled, if significant reductions in GHG emissions were required, or if fuel economy regulations for gasoline vehicles were tightened.     

Energy use and emissions from marine vessels: a total fuel life cycle approach

Regional and global air pollution from marine transportation is a growing concern. In discerning the sources of such pollution, researchers have become interested in tracking where along the total fuel life cycle these emissions occur. In addition, new efforts to introduce alternative fuels in marine vessels have raised questions about the energy use and environmental impacts of such fuels. To address these issues, this paper presents the Total Energy and Emissions Analysis for Marine Systems (TEAMS) model. TEAMS can be used to analyze total fuel life cycle emissions and energy use from marine vessels. TEAMS captures "well-to-hull" emissions, that is, emissions along the entire fuel pathway, including extraction, processing, distribution, and use in vessels. TEAMS conducts analyses for six fuel pathways: (1) petroleum to residual oil, (2) petroleum to conventional diesel, (3) petroleum to low-sulfur diesel, (4) natural gas to compressed natural gas, (5) natural gas to Fischer-Tropsch diesel, and (6) soybeans to biodiesel. TEAMS calculates total fuel-cycle emissions of three greenhouse gases (carbon dioxide, nitrous oxide, and methane) and five criteria pollutants (volatile organic compounds, carbon monoxide, nitrogen oxides, particulate matter with aerodynamic diameters of 10 microm or less, and sulfur oxides). TEAMS also calculates total energy consumption, fossil fuel consumption, and petroleum consumption associated with each of its six fuel cycles. TEAMS can be used to study emissions from a variety of user-defined vessels. This paper presents TEAMS and provides example modeling results for three case studies using alternative fuels: a passenger ferry, a tanker vessel, and a container ship.     

A Life-Cycle Comparison of Alternative Automobile Fuels

ABSTRACT

We examine the life cycles of gasoline, diesel, compressed natural gas (CNG), and ethanol (C₂H₅OH)-fueled internal combustion engine (ICE) automobiles. Port and direct injection and spark and compression ignition engines are examined. We investigate diesel fuel from both petroleum and biosources as well as C₂H₅OH from corn, herbaceous bio-mass, and woody biomass. The baseline vehicle is a gasoline-fueled 1998 Ford Taurus. We optimize the other fuel/powertrain combinations for each specific fuel as a part of making the vehicles comparable to the baseline in terms of range, emissions level, and vehicle lifetime. Life-cycle calculations are done using the economic input-output life-cycle analysis (EIO-LCA) software; fuel cycles and vehicle end-of-life stages are based on published model results.

We find that recent advances in gasoline vehicles, the low petroleum price, and the extensive gasoline infrastructure make it difficult for any alternative fuel to become commercially viable. The most attractive alternative fuel is compressed natural gas because it is less expensive than gasoline, has lower regulated pollutant and toxics emissions, produces less greenhouse gas (GHG) emissions, and is available in North America in large quantities. However, the bulk and weight of gas storage cylinders required for the vehicle to attain a range comparable to that of gasoline vehicles necessitates a redesign of the engine and chassis. Additional natural gas transportation and distribution infrastructure is required for large-scale use of natural gas for transportation. Diesel engines are extremely attractive in terms of energy efficiency, but expert judgment is divided on whether these engines will be able to meet strict emissions standards, even with reformulated fuel. The attractiveness of direct injection engines depends on their being able to meet strict emissions standards without losing their greater efficiency. Biofuels offer lower GHG emissions, are sustainable, and reduce the demand for imported fuels. Fuels from food sources, such as biodiesel from soybeans and C₂H₅OH from corn, can be attractive only if the co-products are in high demand and if the fuel production does not diminish the food supply. C₂H₅OH from herbaceous or woody biomass could replace the gasoline burned in the light-duty fleet while supplying electricity as a co-product. While it costs more than gasoline, bioethanol would be attractive if the price of gasoline doubled, if significant reductions in GHG emissions were required, or if fuel economy regulations for gasoline vehicles were tightened.     

Marginal abatement cost curve for nitrogen oxides incorporating controls,renewable electricity,energy efficiency,and fuel switching

A marginal abatement cost curve (MACC) traces out the relationship between the quantity of pollution abated and the marginal cost of abating each additional unit. In the context of air quality management, MACCs are typically developed by sorting control technologies by their relative cost-effectiveness. Other potentially important abatement measures such as renewable electricity, energy efficiency, and fuel switching (RE/EE/FS) are often not incorporated into MACCs, as it is difficult to quantify their costs and abatement potential. In this paper, a U.S. energy system model is used to develop a MACC for nitrogen oxides (NO_x) that incorporates both traditional controls and these additional measures. The MACC is decomposed by sector, and the relative cost-effectiveness of RE/EE/FS and traditional controls are compared. RE/EE/FS are shown to have the potential to increase emission reductions beyond what is possible when applying traditional controls alone. Furthermore, a portion of RE/EE/FS appear to be cost-competitive with traditional controls.

Implications: Renewable electricity, energy efficiency, and fuel switching can be cost-competitive with traditional air pollutant controls for abating air pollutant emissions. The application of renewable electricity, energy efficiency, and fuel switching is also shown to have the potential to increase emission reductions beyond what is possible when applying traditional controls alone.     

The challenges of reducing greenhouse gas emissions and air pollution through energy sources: evidence from a panel of developed countries

The objective of the study is to investigate the long-run relationship between climatic factors (i.e., greenhouse gas emissions, agricultural methane emissions, and industrial nitrous oxide emission), air pollution (i.e., carbon dioxide emissions), and energy sources (i.e., nuclear energy; oil, gas, and coal energy; and fossil fuel energy) in the panel of 35 developed countries (including EU-15, new EU member states, G-7, and other countries) over a period of 1975–2012. In order to achieve this objective, the present study uses sophisticated panel econometric techniques including panel cointegration, panel fully modified OLS (FMOLS), and dynamic OLS (DOLS). The results show that there is a long-run relationship between the variables. Nuclear energy reduces greenhouse gases and carbon emissions; however, the other emissions, i.e., agricultural methane emissions and industrial nitrous oxide, are still to increase during the study period. Electricity production from oil, gas, and coal sources increases the greenhouse gases and carbon emissions; however, the intensity to increase emissions is far less than the intensity to increase emissions through fossil fuel. Policies that reduce emissions of greenhouse gases can simultaneously alter emissions of conventional pollutants that have deleterious effects on human health and the environment.     

A Comparative Analysis of Emissions Deterioration for In-Use Alternative Fuel Vehicles

Abstract

Although there have been several studies examining emissions from in–use alternative fuel vehicles (AFVs), little is known about the deterioration of these emissions over vehicle lifetimes and how this deterioration compares with deterioration from conventional vehicles (CVs). This paper analyzes emissions data from 70 AFVs and 70 CVs operating in the federal government fleet to determine whether AFV emissions deterioration differs significantly from CV emissions deterioration. An analysis is conducted on three alternative fuel types (natural gas, methanol, and ethanol) and on four pollutants (carbon monoxide, total hydrocarbons, non-methane hydrocarbons, and nitrogen oxides). The results indicate that for most cases studied, deterioration differences are not statistically significant; however, several exceptions (most notably with natural gas vehicles) suggest that air quality planners and regulators must further analyze AFV emissions deterioration to properly include these technologies in broader air quality management schemes.     

Solar Fuels: Vision and Concepts

The world needs new, environmentally friendly and renewable fuels to allow an exchange from fossil fuels. The fuel must be made from cheap and ‘endless’ resources that are available everywhere. The new research area on solar fuels, which are made from solar energy and water, aims to meet this demand. The paper discusses why we need a solar fuel and why electricity is not enough; it proposes solar energy as the major renewable energy source to feed from. The present research strategies, involving direct, semi-direct and indirect approaches to produce solar fuels, are overviewed.     

Solar fuels: vision and concepts

The world needs new, environmentally friendly and renewable fuels to allow an exchange from fossil fuels. The fuel must be made from cheap and 'endless' resources that are available everywhere. The new research area on solar fuels, which are made from solar energy and water, aims to meet this demand. The paper discusses why we need a solar fuel and why electricity is not enough; it proposes solar energy as the major renewable energy source to feed from. The present research strategies, involving direct, semi-direct and indirect approaches to produce solar fuels, are overviewed.     

Renewable Energy

The Energy Committee of the Royal Swedish Academy of Sciences has in a series of projects gathered information and knowledge on renewable energy from various sources, both within and outside the academic world. In this article, we synthesize and summarize some of the main points on renewable energy from the various Energy Committee projects and the Committee’s Energy 2050 symposium, regarding energy from water and wind, bioenergy, and solar energy. We further summarize the Energy Committee’s scenario estimates of future renewable energy contributions to the global energy system, and other presentations given at the Energy 2050 symposium. In general, international coordination and investment in energy research and development is crucial to enable future reliance on renewable energy sources with minimal fossil fuel use.     

Effects of Atmospheric Stability and Wind Direction on the Correlation of Wind Speed

Abstract

In return for a temporary waiver from converting five vehicles to operate on compressed natural gas (CNG) for the Denver Clean Fuels program, the University of Denver identified, tested, repaired, and retested nine employee commuter vehicles. The results of the study validated the concept that employer-based identification and repair programs can be carried out in a cost-effective way. On average, each repaired vehicle removed fifty times more carbon monoxide (CO) emissions from Denver air than each CNG conversion. The average cost of each repair was eight times less than the average cost of each conversion. The average fuel economy benefit from the repairs was enough to pay for the average cost of repairs in less than three years of normal driving. When the expected lifetimes of repairs and conversions are included, the targeted repair program appears to be over sixty times more cost-effective as a CO emissions reduction strategy than CNG conversion.     

Options for Change in the Australian Energy Profile

Climate change is occurring largely as a result of increasing CO₂ emissions whose reduction requires greater efficiency in energy production and use and diversification of energy sources away from fossil fuels. These issues were central to the United Nation climate change discussions in Durban in December 2011 where it was agreed that a legally binding agreement to decrease greenhouse gas emissions should be reached by 2015. In the interim, nations were left with the agreement reached at the analogous 2009 Copenhagen and 2010 Cancun meetings that atmospheric CO₂ levels should be constrained to limit the global temperature rise to 2 °C. However, the route to this objective was largely left to individual nations to decide. It is within this context that options for reduction in the 95 % fossil fuel dependency and high CO₂ emissivity of the Australian energy profile using current technologies are considered. It is shown that electricity generation in particular presents significant options for changing to a less fossil fuel dependent and CO₂ emissive energy profile.     

Air Quality Management in Los Angeles: Perspectives on Past and Future Emission Control Strategies

The 1988 Air Quality Management Plan was approved by the Board of the California South Coast Air Quality Management District in March 1989. The District comprises the counties of Los Angeles, Orange, and Riverside, and the non-desert portion of San Bernardino county. Emissions reductions in the past have lead to significant improvement in air quality despite large increases in growth. However, the District, largely because of continuous growth, currently violates the air quality standards for ozone, carbon monoxide, nitrogen dioxide, and respirable particulate matter (PM₁₀). Based upon the AQMP, reduction of approximately 80 percent in emissions of oxides of nitrogen and volatile organic compounds is required to bring the District into compliance with all air quality standards in the next twenty years.

Achieving compliance will necessitate the use of advanced technologies, as well as some changes in lifestyle and management practices. Advanced technologies, including the use of electric vehicles powered by batteries or fuel cells, the use of cleaner burning fuels and advanced combustion modifications, and treatment of surface coatings and solvents are included in the AQMP. The Technology Advancement Office in the District was created to work with industry, universities, research institutes, and other local, state and federal agencies to identify, evaluate, and promote low emitting fuels and technologies. In addition to electricity, fuels burning cleaner than conventional gasoline or diesel are being tested to obtain emissions and durability data so that rational choices can be made for the future. Compressed natural gas, methanol and liquefied petroleum gas are considered to be cleaner burning fuels for current applications. Ethanol, butane, and various oxygenated blends are being evaluated, and the broader application of solar energy and hydrogen are being investigated.

The impact of various cleaner burning fuels on air quality is being addressed. To date, methanol is the only fuel for which results are available. These results indicate that methanol use in vehicles—with control of formaldehyde emissions below 15 mg/mile for light-duty vehicles—can provide air quality benefits for all criteria pollutants and certain air toxics. These benefits are greater for M₁₀₀ than M₈₅.

Several District advanced technology programs are described, including a reduction in emissions from paints and coatings, and the demonstration of electric vehicles.     

Renewable energies in electricity generation for reduction of greenhouse gases in Mexico 2025

This study presents 4 scenarios relating to the environmental futures of electricity generation in Mexico up to the year 2025. The first scenario emphasizes the use of oil products, particularly fuel oil, and represents the historic path of Mexico's energy policy. The second scenario prioritizes the use of natural gas, reflecting the energy consumption pattern that arose in the mid-1990s as a result of reforms in the energy sector. In the third scenario, the high participation of renewable sources of energy is considered feasible from a technical and economic point of view. The fourth scenario takes into account the present- and medium-term use of natural-gas technologies that the energy reform has produced, but after 2007 a high and feasible participation of renewable sources of energy is considered. The 4 scenarios are evaluated up to the year 2025 in terms of greenhouse gases (GHG) and acid rain precursor gases (ARPG).     

Chemical Characterization and Source Identification of Polycyclic Aromatic Hydrocarbons in Aerosols Originating from Different Sources

To put waste-to-energy (WTE) in perspective, it is important to see how it measures up environmentally to other power generation utility sources.

This paper compares actual WTE facility emissions with those from fossil fuel combustion utility sources. This comparison is made on an electricity production basis, such as a pound of pollutant per megawatt-hour of net electricity generated, for each power generation source.